2. AIMS OR GOALS
• Sedation and anxiolysis.
• Analgesia and amnesia
• Antisialogague effect
• To maintain haemodynamic stability
• To prevent aspiration
• Decrease postoperative nausea &
vomiting
• Prophylaxis against allergic reaction.
3. Primary goals of pre-medication
1. Anxiolysis to amnesia to sedation.
2. Analgesia
3. Antisialogogue action
4. Antiemetic
5. Antiallergic
6. Decrease of gastric fluid volume
7. Increase of gastric fluid PH
8. Haemodynamic stability
4. Secondary goals of pre-medication
1. Post operative pain relief
2. Post operative antiemesis
3. To decrease vagomimetic effect of
anaesthetic technique
4. To decrease vagomimetic effect of
anaesthetic agents like halothane,
scoline.
5. • Pt age & weight.
• Physical status.
• Level of anxiety and pain.
• Previous H/o drug use and abuse.
• H/o preoperative nausea/vomiting/motion
sickness.
• Drug allergies.
• Elective & emergency surgeries.
• Inpatient &out pt status.
Factors for selecting premedication
6. Pediatric / Adult
• More difficult to prepare
• Oral route preferred.
• Frequent use of vagolytics.
• Children > 1 yrs benefit from sedative
premedication.
7. TYPES OF PREMEDICATION
Psychological premedication
Pharmacological premedication.
Benzodiazepines:
o very popular
o Produces amnesia/sedation, reduce anxiety.
o Little resp depression.
o Diazepam,lorazapam,midazolam.
8. MOA:
Exert their effect by occupying the B.
receptor in cns and spinal cord that
modulates GABA , major inhibitory
neurotransmittor in brain.
Onset & Duration of action:
Midazolam/Diazepam= 30-60 sec
Lorazepam = 60-120 sec.
Diazepam t/2 = 30-60hrs.
Midazolam t/2= 2 hrs
Lorazapam t/2=20-25 hrs.
9. EFFECT
Sr
no
System involved Diazepam Lorazepam Midazolam
1 CNS
i)CBF & CMR
ii)Seizere thres
Dec
Increase
Dec
increase
Dec
incre
2 Respiratory
i) Depression Dec Dec ++
3 CVS
• BP
• HR
Dec
---
Dec
---
++dec
Dec/inc
10. Doses:
Midazolam:
out patient: 7.5-15 mg oral
5-7mg IM
1-2mg IV.
Pediatric : 0.05-0.1 mg/kg/oral/IM/IV
0.2mg/kg/Intranasal/sublingual
Lorazepam:
OP: 1-3mg oral
IP : 1-5mg/2-4mg IM/IV
children 0.03-0.1mg/kg/IV/IM/Oral.
11. SIDE EFFECTS:
1. Hypnotic doses causes
dizzinesss,vertigo, ataxia, disorientation,
prolongation of reaction time.
2. Midazolam causes respiratory
depression.
3. Dia/Lora Resp depress+ venous irritation
& thromphebilitis.
4. Synergestic action of Midazolam & spinal
A with respect to ventilation.
5. Causes flacidity and resp dep in
neonates.
16. Tramadol:
• Centrally acting analgesic.
• Affinity for mu receptor modest.
• Inhibits reuptake of NA and 5-HT, thus
activates monoaminergic spinal inhibition
of pain.
Effect:
• It causes < resp depression, sedation,
constipation, urinay retention & rise in
intrabiliary pressure.
• Used as antishivering agent.
17. Side effect:
• Nausea & vomiting.
• Dizziness
• Dry mouth.
Dose:
• Children 1-2mg/kg.
• Adult 50-100mg oral/IM/IV.
18. Ondansetron:
Prototype of serotonin antagonist drug.
MOA:
• Blocks depolarizing effect of 5-HT through
5HT3 receptors on vagal afferents in GIT,
NTS,CTZ.
• Blocks emetogenic impluses at
peripheral/central.
• Does not block dopamine receptors,
superior to Metoclopramide.
19. Pharmacokinetics:
• Oral bioavailability is 60-70%
• Plasma t ½ is 3-5 hrs
• Duration of action 4-12 hrs.
Dose:
• Children 0.05-0.1mg/kg/oral/IV/IM
• Adult 4-8 mg IM/IV.
Side effects:
• Headache
• Abdominal discomfort
• Mild constipation or diarrhoea.
20. Promethazine:
It is H1 antihistaminic drug used for its
anxiolytic, antiemetic, anticholinergic
properties.
MOA:
• Blocks H 1 receptors in CNS and
peripheral tissue.
Effects:
1. CNS:- produce sedation by blocking H 1
receptors in CNS. Antiemetic effect by
blocking H 1 in chemoreceptor trigger
zone.
21. 2. CVS:- H 1 mediated slowing of A-V
conduction is noted.
3. Smooth muscle:- smooth muscle
relaxation in lung, intestine, uterus, blood
vessels.
4. Adrenal medula causes < in release of
catecholamine.
5. Blocks muscarinic receptors and
decreases acetylcholine release.
Dose:
• adult 25-50 mg oral/IM/IV
• Children 1mg/kg oral/IV/IM
22. Side effects:
1. Diminished allertness, concentration.
2. Light headedness.
3. Motor incoordination, fatigue, tendency
to fall asleep.
4. Antichlonergic side effects.
24. H2 receptor antagonist:
Used as premedication as it decreases
gastric juice volume and aspiration. It
also increases gastric pH.
Commonly used are
1. Cimitedine
2. Ranitidine
3. Famotidine
MOA:
• Blocking H2 histaminic recep in GIT,
Heart and bronchial smooth muscle.
25. COMPARISON OF H2 BLOCKERS
Cimetidine Ranitidine Famotidine
Plasma t ½ 2-3 hrs 2-3 hrs 2.5-3.5 hrs
Duration + ++ +++
10-12 hrs 12-14 hrs 14-16 hrs
Potency + ++ +++
5 times
>cimitedine
5-8 times >
ranitidine
CNS effect +++ + +
Endocrine
effects
+ -- --
27. Side Effects:
• headache
• Dizziness
• Bowel upset
• Dry mouth
• Bolus IV inj. Causes bradycardia, arrhythmia,
cardiac arrest,
• Antiandrogenic side effect- loss of
libido,gynecomastia, impotence(> cimitedine)
• CNS effect seen with cimitedine like confusion,
restlessness,delirium. Ranitidine and famotidine
dose not cross BBB.
28. Antacids:
Basic substances which neutrilizes gastric acid
and raise pH above 2.5
1. Systemic antacids: sodium bicarbonate,
sodium citrate.
2. Nonsystemic antacids mag.hydroxide,
mag.trisillicate, aluminium hydroxide gel.
Proton Pump Inhibitors:
MOA:
Block the final pathway in acid secretion in
stomach by H+ - K+ ATPase enzyme blockade
29. Pharmacokinetic:
• Plasma t ½ is 1 hr.
• Oral absorption is only 50%.
Dose:
Omeprazole – 20-60 mg OD
Pantoprazole – 40 mg IM/IV.
30. Anticholinergic agents:
1. Atropine.
2. Scopolamine.
3. Glycopyrolate.
MOA:
• Blocking the action of ACH on autonomic
receptors and in CNS exerted through
muscarinic receptors.
Pharmacokinetics:
• Rapidly absorbed orally.
• Atropine/hyoscine crosses BBB, but not
pyrolate.
• Absorption through mucosal surface.
